Most computers use disk drives to store data. A disk drive typically includes platters that the data is stored on and a recording head that is used to write data onto the platters and to read the data from the platters. The recording head is manufactured to include what is commonly known as a slider that has aerodynamic properties to fly over a platter. A slider flies over a location on a platter for the purpose of writing data to that location or reading data from that location.
FIG. 1 depicts a side view of a conventional slider. The slider 100 includes a write head 108 for writing data to a platter and a read sensor 106 for reading data from a platter. The read sensor 106 has a height, which is commonly known as a stripe-height 102. The air bearing surface 104 (ABS) of the slider 100 provides the aerodynamic properties that enables the slider 100 to “fly” over a platter and to be positioned over a desired location on the platter.
In order for the slider 100 as well as the read sensor 106 and the write head 108 to function properly, the ABS 104 needs to be very flat and smooth and the read sensors 106 need to have an appropriate stripe-height 102. A lapping plate is used for grinding and/or polishing the ABS 104 (commonly referred to as the “lapping process”) in order to achieve the desired smoothness and the desired stripe-height 102. A lapping plate typically has abrasive particles, such as diamond particles, on its surface that can be used to remove material from the slider 100. Diamonds are typically embedded into the plate surface using what is commonly known as a “charging process.” It is necessary that the lapping plate be able to remove a sufficient amount of material from the ABS 104 of the slider 100 within an appropriate amount of time.
The dimensions of read heads are shrinking in order to achieve greater recording densities. The smaller dimensions of the read heads makes the sensors 106 more susceptible to damage from mechanical stress that results from the lapping process. Lapping process inherently is a mechanical stress process since the diamond particles have to remove materials from sliders. The quality of a lapping plate may not be good enough to be used for lapping sliders 100 when the lapping plate damages read sensors 106 due to excessive stress even though the lapping plate is very capable of removing material. For example, large scratches may form on the surface of a lapping plate due to the charging process or lapping process. Another example is that many small diamond particles can cluster together to effectively form large diamond particles. In both cases, the stress on read heads may be sufficient to damage sensors 106.
Typically, sliders 100 are removed from the lapping process, washed and placed in an external tester to determine their (100) magnetic performance and to determine whether the sensors 106 have been damaged by the lapping process. Removing sliders 100 from the lapping process in order to test the sliders 100 makes it difficult to provide fast feed-back to the lapping process.
For these and other reasons, there is a need to evaluate the quality of a lapping plate. For these and other reasons, there is also a need to reduce mechanical stress caused by the lapping process which can result in damaged sensors associated with sliders. For these and other reasons, there is also a need to provide fast feed-back to the lapping process.